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Shuttle, Space Station Flex Robotic Arms

Posted on: Friday, 14 July 2006, 21:00 CDT

By SETH BORENSTEIN

HOUSTON - The space shuttle Discovery and the international space station flexed their robotic arms repeatedly Friday, racking up a record for robotics in space and taking yet one more look for damage to the shuttle's heat shield.

Down at Mission Control, engineers debated what to do about a leaking auxiliary power unit, one of three needed to control the hydraulic steering and braking maneuvers for landing the shuttle. Discovery is scheduled to touch down Monday morning at the Kennedy Space Center.

Deputy shuttle program manager John Shannon said it was unclear whether harmless nitrogen or potentially dangerous hydrazine fuel is leaking from the tank for the first auxiliary power unit. He suspects it is nitrogen, which would be "no issue at all."

The leak is so small that even if it is hydrazine, it is well below any flammability threat, Shannon said. The power unit will be tested in orbit Sunday. If the leak worsens, it could affect touchdown plans.

Neither of Discovery's two other power units appeared to be leaking, Shannon said. One, however, was getting close to overheating, considered a minor problem.

It was just another day in space for Discovery's robot operators Stephanie Wilson and Lisa Nowak, whom Mission Control called the "robo chicks."

During the first 11 days of Discovery's flight, Nowak and Wilson set an unofficial record for robotic arm activity, all of it going smoothly, mission controllers told the duo Friday morning.

The compliment came a tad too soon. Hours later, minor problems with the space station's robotic arm put Wilson and Nowak behind schedule on their big inspection of the day, looking at the shuttle's left wing for damage from dust-sized meteorites and small pieces of space junk.

The inspection used a laser sensor attached to the extension that doubles the length of the 50-foot robotic arm.

When Mission Control praised Discovery for getting the inspection finished, commander Steve Lindsey answered: "Robo chicks take care of it again."

Engineers will not know until Saturday if the shuttle gets its expected all-clear for landing. The shuttle undocks from the space station that day, and the robotic arm will be hauled out again to look at the left wing and the nose cap - something easier to do when detached from the space station.

When asked about being dubbed robo chicks, Nowak and Wilson laughed.

"We've actually learned a lot while we've been up here," Nowak told CBS News. "We trained for a couple of years before we got up here."

Mission controllers gave Discovery the option of skipping Friday's inspection because of the earlier problems, telling commander Steve Lindsey that the examination was not mandatory.

Lindsey said he would rather get it done and get less sleep. Then Nowak and Wilson moved the shuttle arm around the wing, moving quietly and quickly. As of Friday night, about half the data from the inspection had been transmitted to ground controllers.

Nowak and Wilson performed flawlessly at the task, which is like controlling a video game stick and being an air traffic controller at the same time, said NASA robotics operator Simon Aziz.

"It's a piloting skill," Aziz told The Associated Press. "You're flying the joystick and the operator is trying to absorb information off all the screens."

Another job that went well in space was moving nearly seven tons of supplies between the space station and the shuttle. The crew moved new equipment aboard the station and removed old items to bring back.

The transfer was supposed to take 128 hours, but Discovery's astronauts efficiently did it in 93 hours, space station lead flight director Rick LaBrode said. NASA is going to quiz the crew when they get back to Earth to see how they worked so fast.

"We got our money's worth out of them," LaBrode said, adding that the entire mission has been outstanding.

That's the way the crew sees it, too.

"We've got a great ship and it's ready to come home. It's going to be a safe landing," pilot Mark Kelly said in interviews. "Based on what we've seen so far and what the risk is, I think all of us feel really comfortable."

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On the Net:

http://spaceflight.nasa.gov

Source: Associated Press/AP Online

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